Impregnation of electric cables



Dec. 29, 1936.

' IMPREGNATION OF ELECTRIC CABLES Filed July 19, 1932 2 Sheets-Sheet 1INVENTORS THOMAS R. sco'r'r BY JOHN K. WEBB ATTORNEY T. R. SCOTT El AL2,065,927-

Dec. 29, 1936. R sc T r AL 2,065,927

IMPREGNATION OF ELECTRIC CABLES Filed July 19, 1952 2 Shets-Sheet 2INVENTORS THOMAS R. SCOTT BY JOHN K. WEBB ATTORNEY Patented Dec. 29 1936UNITED STATES PATENT OFFICE IMPREGNATION Oli' ELECTRIC CABLES ThomasRobertson Scott and John Kranss Webb,

Aldwych, London, England, asaignors to International Standard ElectricCorporation, New York, N. Y., a corporation of Delaware Application July19, 1932, Serial No. 623,310

In Great Britain October 12, 1931 14 Claims. (Cl. 173--264) 4 upon thepressure in the chamber 2 below the.

. oil to the cable and another object is to provide a ready andpractical method and system for effecting said impregnation.

According to one feature of the invention a system or method of feedingunder pressure de-- I gasifled oil or the like into a cable isarrangedso that the rate of degasiiication of the oil is determinedautomatically or continuously by the cableconsumption.

Another feature is maintaining substantially uniform the pressure in the.oil as it is fed to the cable irrespective of the rate of oilconsumption by the cable.

According to another feature of the invention the system or methodcomprises a pump operating to discharge a supply of degasifled oil froma source to a cable or to intermediate appara-, tus before reaching acable, said pump also being adapted to discharge a supply of oil to saidsource for degasiflcation.

Another feature of the invention is a particular form of thedegasiiierunit as will be hereinafter explained.

These and other features of the invention will .be more readilyunderstood from a perusal of the following description having'referenceto the accompanying drawings in which Figure 1 schematically illustratesa system according to the invention. Figure 2 illustrates schematicallya form of the degasifier unit which may be employed in the system ofFigure 1 and Figure 3 illustrates a system which is a modified form ofthat shown in Figure i.

In Figure 1 a piston l is adaptedto operate in the cylinder 2. Thiscylinder has an inlet valve 3 over which the cylinder communicates withan inlet pipe 4 connected to some suitable oil supply 5. The source 5 isshown schematically and may comprise any known arrangement formaintaining a head of oil to the inlet pipe 4. An outlet valve 6communicating with the pipe 1 aflords access of oil from the chamber 2to a reservoir 8 connected to a degasifier 8 from which 011 is fed to areservoir iii. A pipe ll connects the outlet of the reservoir ill to theinlet valve ll of the chamber 2. .A pipe i3 maintains continuousconnection between the chamber 2 and a pressure compensating chamber it.This chamber has a. piston i5 whose leve l depends stroke of the pistonl.

piston I. The chamber H has an outlet valve l8 leading to a cock whichmay be used to couple the cable to this outlet of the chamber l4. s

Another outlet valve ll leads to pipes i8 and I9 which communicate withthe reservoir 20, degasifler 2| and the reservoir 22, the latter beingconnected over a pipe 23 and inlet valve 24 to the chamber II. Anauxiliary pipe 28 containing a hand operated regulating valve 25 alsoconnects the chamber ll with the pipe II, and forms a regulating by-passaround the chamber ll, pipe I! and the oil sealing system 3|. The pistonl carries weights 26 and be operated over a magnetic clutch 29 by amotor 30.

The various cocks in the system are preferably this seal system iseffected over the pipe It the rectangle 3i representing schematicallythe entire oilv seal system.

The operation of the arrangement is as follows:-

Theincoming oil is fed from the source 5 and is preferably under agravity head and at some degree of reduced gas content (say 50%),designated herein as stage 0 The downward stroke of the piston i sucksthe oil into chambei- 2 through the non-return valve 3. The displacementcapacity of this chamber is designed to give the desired volume 12 whichitis proposed 'to circulate through the system by each The upward'strokeof the said piston causes oil to. pass through the non-return valve 0 tothe reservoir 8 which preferably has a capacity in excess of V the exactvalue being calculated in terms of the rate of flow in the degasifler 9and'the maximum number of strokes per unit of time which said piston maybe required to make. The'oil from the de gasifler 9 collects-inthereservoir ill which is preferably of about'the same capacity as thereservoir 8. On the upward stroke of the piston l oil (hereinaftertermed stage 1 oil") is sucked from the reservoir It into the chamber 2through the pipe II and non-retum valve II. The suction is caused by theupward motion of the piston l and is limited to the second half of theupward stroke by a sleeve 32 which is attached to the piston. i-

The maximum capacity of chamber 2 below the piston is 2V and theremaining volume V required is obtained by drawing back. during thefirst half of the stroke, a volume v equal to is connected bymeans of arope 21 to a capstan 28 which may .oil sealed and a continuous supply ofoil to the displacement volume of chamber I4 below the piston in theraised position. The upward stroke of the piston is made byautomatically switching-in an electric motor and winding gear when thepiston 'I reaches the bottom of its stroke. The switchingin may becarried out by starting up a motor which is coupled to the winding gear,or by actuating a magnetic clutch between the winding gear and a motorwhich is running continuously. The winding gear is switched out at thetop of the pistons stroke, and the downward stroke is controlled by theweight system (regulating the pressure) and the demand of the cable, orthe impregnating system for oil. The downward stroke sucks stage 0 oilinto chamber 2 as described above, and also forces stage 1 oil fromchamber 2 to chamber I4. The piston I5 is thus caused to move upwards.The piston I5 reaches the top of its stroke dur-' ing the first half ofthe downward stroke of the piston I. At thispoint the sleeve attached topiston I5 exposes an outlet in chamber I4, and during the second half ofthe downward stroke of piston I, a volume V of stage 1 oil is passedfrom chamber 2 via chamber I4 to reservoir 20. In passing from chamberI4 to reservoir 20 the oil traverses a non-return valve and the oil sealsystem 3I. 23 is the reservoir for the stage 2 degasifier and is areplica of reservoir 3. The oil passes through the degasifier asdescribed above to reservoir 22 and is drawn thence to chamber I4through a non-return valve. The suction in this case is caused by thedownward stroke (under gravity) of piston l5 during the first halfstroke upwards of piston I. From chamber I4 the oil is forced underpressure through a non-return valve and a hand operated shut-off" valveto the cable or to the impregnating system. The pressure is suppliedthrough piston I5 during the downward stroke of piston I. The maximumvolume of cham ber' I4 (below its piston) is V so that as the cabletakes this volume the stage 2 degasifier is replenished by thecompletion of the stroke of piston I, and, as described above, a freshsupply of oil (volume V) is taken into the system and passed through thestage 1 degasifier.

In place of the sleeve valves shown attached to pistons A and B, it maybe convenient to utilize outside valves controlled by the action of thepiston rod of piston I. These valves would be operated to open duringthe second half of the upward and downward strokes respectively ofpiston I, say by a sleeve action on the valve rod such that relativemotion between the valve rod and the piston I rod was permitted duringthe first half of the upward stroke.

The degasifier is illustrated in more detail in Figure 2. It is built upof a plurality of fluted cylinders 33 which are coupled together overliquid seals 34. An inlet valve 35 is provided as shown so that oil mayfiow into the cylinder. The spreader 36 ensures that the oil is broughtquickly into contact with the inner surface of the cylinder. Vacuum isapplied over the duct 31. 38 is a float valve which normallyopens theduct 3'! to the body of the cylinder 33. Should, however, there be anexcess of oil in this cylinder the float would be raised to cut offcommunication between the cylinder and the duct 3! so that there islittle danger of oil passing through the suction duct. The oiltraversing the large surface of the fluted cylinder 33 loses a largeproportion of its occluded gas. Reaching the oil seal 34 the partiallydegasified oil may pass forward to the next cylinder 33 which is similarto'33. As many such stages as desired may be used. The oil being finallywithdrawn from the outlet valve 43.

A modified form of system is illustrated in Figure 3, wherein in thiscase twin cylinders are employed working in opposing phase. Theoperation of the pistons 01' these cylinders may be identical with thatalready described in connection with Figure 1 and will therefore not befurther elucidated. In this figure oil from the reservoir 4I may passthrough pipe 63 into either of the chambers 42 or 43 according to themotion of the pistons in these chambers. The device affordingcommunication between the chambers 42 and 43 and the degasiflers andreservoirs is clearly illustrated and it is thought that theconstruction of the system will be readily understood from a descriptionof its mode of operation. Assuming that the clutch has just engaged themotor 44 the piston 45 would begin to rise. In doing this oil would besucked in through non-return valve 6| from the pipe 46 leading from thereservoir 41. This reservoir 41 receives degasified oil of the secondstage from the degasifier 43. On this upstroke of the piston 45 oil isforced from above said piston through valve 62 over pipes 43, 63 and 64into the degasifier 43. During the time the piston 45 is ascending, thepiston 50 in chamber 43 descends. In so doing a charge of oil is takeninto the upper part of chamber 43 from the reservoir 4I through pipe 63and non-return valve 65 and below the piston 53 oil is dischargedthrough valve 66 into a duct 5| leading to a cock 52 attached to thecable which is being impregnated. A supply of oil is also sent throughpipe 61 surrounding duct 5I and into the ducts 53 and 68 for sealingvalves 63 and 10 in a manner such as described in connection withFigure 1. A pipe 12 connecting pipe 61 to pipe 33 serves as a pressurerelief in the valve sealing system, a hand operated valve I3 beingprovided in pipe I2 to regulate the fiow of oil therethrough. In thereverse movements of the pistons 45 and 53 an action takes place similarto the above, the roles of the two pistons being reversed, and it willthus be seen how oil may be fed from a supply tank (not shown) through apipe 14 containing a hand operated regulating valve 15 into the roughdegasifier 54, be passed through the fine degasifier 43 and finally bepumped into the cock 52. Each of the pistons 45 and 50, in addition tobeing provided with weights 26, 26 as is the piston in Figure l, is

surrounded by a compressible bellows-like stufring box oil.

Although the invention has been described with reference to specificembodiments it is to be understood that many modifications may be madewithout exceeding the scope of the invention.

What we claim is:

l. The process of impregnating a cable with oil which comprises drawingthe oil from a source of supply, degasifying the oil so drawn, feedingsuch degasified oil under pressure to the cable, and regulating the rateof degasification in accordance with the rate of consumption of oil bythe cable.

2. The impregnating process according to claim 1 characterized by thestep of automatically maintaining the degasified oil at a; substantiallyuniform pressure as 16 which serves to prevent leakage of it is fed tothe cable 7 source, a degasifler, connecting means for a cable to beimpregnated, and means for causing said pump to discharge degasiiied oilfrom the degasifier into the cable connecting means and to dischargeoilfrom said source into said degasiiier for degasiflcation.

4. Apparatus for forcing degasiiled oil into a cable from degasifyingunits characterized in this that the feeding of the oil to'the cable andto the degasifying units is effected by one and the same pump. I

5. Apparatus as claimed in claim 3 characterized bythe provision ofmeans for causing the pump to operate under gravitational force.

6. Apparatus as claimed in claim 3 wherein a plurality of pumps areemployed to render the feed to the cable continuous.

'7. An arrangement for feeding degasifled oil to a cable comprising afirst stage degasiiler, a second stage degasiiier, a pump forcontrolling and efiecting the flow of' oil from the first degasifler tothe second degasifier at a rate closely approaching that of absorptionby the cable connecting means, and means for delivering the gasified oilfrom the second desasifier to the cable connecting means.

8. An arrangement according to claim '7 wherein a pressure compensatingchamber works with said pump to maintain the requisite pressure ofsupply. in different parts 0! the system.

9. A degasifler for use in an arrangement according to claim 7characterized by having a plurality of fluted cylinders in stages, aliquid seal adapted to couple two adjacent cylinders,

inlet duct for the first cylinder, an outlet duct for the last cylinder,and means for applying vacuum to each stage whereby oil introducedthrough the inlet duct and traversing each stage in turn reaches theoutlet duct in a degasiiied state. a

10. Apparatus for feeding degasifled oil into a cable comprising aplurality of fluted cylindersin stages, a liquid seal adapted to coupletwo adjacent cylinders, means for applying vacuum to each stage, meansadapted to introduce oil into each stage in turn, means adapted toprevent oil from having access to the vacuum ducts, cable 5 connectingmeans, and means to deliver the degasifled oil to the cable connectingmeans.

I 11. Apparatus for feeding degasifled oil into a cable comprising aplurality of fluted cylinders in stages, a liquid seal adapted toconnect two stages, means .for applying vacuum to each stage, meansadapted to introduce oil into each stage in turn, a float valve adaptedto prevent oil from having access to the vacuum ducts, means adapted tobring oil into intimate contact with the walls of the fluted cylinders,and means for delivering oil from the last stage into the cable.

12. Apparatus for feeding degasifled oil into a cable comprising anarray of degasifier units adapted to permit ready assembly of unitsaccording to the desired capacity, each unit comprising a plurality offluted cylinders in stages, a liquid seal adapted to couple the adjacentcylinders, inlet and outlet ducts, means for applying vacuum to eachstage whereby oil traversing each stage in turn reaches an outlet ductin a degasifled state, cable connecting means, and means for deliveringdegasifled oil from the last degasifler station to the cable connectingmeans.

13. The process of impregnating a cable with oil which comprisesobtaining the oil from a source of supply, degasifying the oil soobtained, {feeding the degasiiied oil under pressure to 'the cable, anddetermining and regulating the rate of degasification by the rateofconsumption of the oil by the cable. v

l4.The process of impregnating a cable with oil which, comprisesobtaining the oil from a source of supply, degasifying the oil soobtained, feeding the degasifled oil under pressure to the cable,controlling the continuous 'degasifying of the oil during consumption ofthe deg'asifled oil by the cable and regulating the rate ofdegasiflcation in accordance with the rate of consumption.

THOMAS ROBERTSON SCOTT. JOHN KRAUSS WEBB.

